Head-to-Head Comparison between [(68)Ga]Ga-DOTA.SA.FAPi and [(18)F]F-FDG PET/CT Imaging in Patients with Breast Cancer

This study aimed to compare the diagnostic performance of [(68)Ga]Ga-DOTA.SA.FAPi with that of [(18)F]F-FDG PET/CT in detecting primary and metastatic lesions of breast cancer. [(18)F]F-FDG and [(68)Ga]Ga-DOTA.SA.FAPi PET/CT scans of histologically proven breast cancer patients were compared according to patient-based and lesion-based analysis. Forty-seven patients with a mean age of 44.8 ± 9.9 years (range: 31–66 years) were evaluated. A total of 85% of patients had invasive ductal carcinoma, and 15% had invasive lobular carcinoma. The tracer uptake [SULpeak, SULavg, and the median tumor-to-background ratio (TBR)] was significantly higher in [(68)Ga]Ga-DOTA.SA.FAPi than with [(18)F]F-FDG PET/CT for lymph nodes, pleural metastases, and liver lesions (p < 0.05). However, for brain metastasis, only the median TBR was significantly higher (p < 0.05) compared to [(18)F]F-FDG. In patient-based analysis the sensitivity of [(68)Ga]Ga-DOTA.SA.FAPi PET/CT was higher, but not significant than that of [(18)F]F-FDG PET/CT in the detection of both primary tumors and metastatic lesions. According to lesion-based analysis, on diagnostic CT, 47 patients had 44 primary tumors, 248 lymph nodes, 15 pleural, 88 liver, and 42 brain metastases. [(68)Ga]Ga-DOTA.SA.FAPi scan identified more abnormal lesions than [(18)F]F-FDG in all the primary and metastatic sites with a maximum marked difference in the primary site [88.6% vs. 81.8%; p-0.001], lymph nodes [89.1% vs. 83.8%; p-0.0001], pleural metastases [93.3% vs. 73%; p-0.096] and brain metastasis [100% vs. 59.5%; p-0.0001]. [(68)Ga]Ga-DOTA.SA.FAPi PET/CT was superior to [(18)F]F-FDG PET/CT in the imaging of breast cancers.